This invention relates to apparatus for X-ray analysis which uses a composite monochromator having combined two elliptic monochromators, the composite monochromator being arranged between an X-ray source and a sample, and relates to apparatus for supplying X-rays which uses a composite monochromator having combined two elliptic monochromators.
U.S. Pat. No. 6,249,566 discloses apparatus for X-ray analysis which uses a composite monochromator having combined two elliptic monochromators, the composite monochromator being arranged between an X-ray source and a sample. The two elliptic monochromators are joined with each other side by side. Each of the two elliptic monochromators has a reflection surface made of a synthetic multilayered thin film whose period or d-spacing varies continuously along an elliptic-arc. The X-ray source is a microfocus X-ray source having an effective focal spot size of less than 30 micrometers.
Since the prior-art apparatus for X-ray analysis mentioned above uses the microfocus X-ray source having a focal spot size of less than 30 micrometers, even if the distance between the X-ray source and the monochromator becomes smaller (preferably less than 30 mm), the breadth of incidence angle, which depends upon the effective focal spot size of the X-ray source, becomes satisfactorily within the range of the half-value width of the diffraction peak of the elliptic monochromator, so that the X-rays reaching the elliptic monochromator are utilized effectively with no loss. Furthermore, since the distance between the X-ray source and the elliptic monochromator can be smaller, the capture angle of incident X-rays on the elliptic monochromator is increased, so that the X-ray intensity focused on the sample can be greatly increased.
Since the prior-art apparatus for X-ray analysis mentioned above has a monochromator coming closer to the X-ray source than 30 mm preferably, the X-ray source to be used is of a stationary-target type. The microfocus target of the stationary type, however, has a limitation in receiving power which is supplied to an X-ray tube, so that it is difficult to increase the input power in order to obtain a higher X-ray intensity focused on the sample.
It is an object of the present invention to provide apparatus for X-ray analysis and apparatus for supplying X-rays each having a combination of a rotating target X-ray tube and the above-mentioned composite monochromator under an optimum condition in which a higher X-ray intensity focused on a sample can be expected.
Apparatus for X-ray analysis according to the invention has an X-ray source generating an X-ray beam which is reflected by a monochromator and thereafter incident on a sample, and is characterized below. The X-ray source is a rotating target X-ray tube having a rotating target which has an effective focal spot size of 40 to 100 micrometers. The monochromator is a composite monochromator having a first and a second elliptic monochromators joined with each other side by side. Each of the elliptic monochromators has a first focal point at which the X-ray focal spot on the target is disposed, and a second focal point at which the sample is to be disposed. Each of the first and second elliptic monochromators has a reflection surface made of a synthetic multilayered thin film in which layer boundaries, which contribute to diffraction, are parallel to the reflection surface and d-spacing varies continuously along an elliptic-arc so as to satisfy the Bragg""s equation for X-rays with a predetermined wavelength at any point of the reflection surface. The shortest distance between the X-ray focal spot on the target and the composite monochromator is 40 to 100 mm.
Since the apparatus for X-ray analysis according to the invention has a combination of the rotating target X-ray tube and the composite monochromator in which the effective focal spot size on the target is 40 to 100 micrometers and the shortest distance between the X-ray focal spot on the target and the composite monochromator is 40 to 100 mm, an X-ray intensity focused on the sample is increased with the maximum efficiency.
This invention may be applied to not only apparatus for X-ray analysis, in which X-rays are incident on a sample to be analyzed, but also apparatus for sullying X-rays in other applications. The apparatus for supplying X-rays may be used, for example, for (1) apparatus for X-ray analysis, (2) apparatus for X-ray irradiation in the fields of material processing, medical care and so on, and (3) apparatus for X-ray lithography. With the apparatus for supplying X-rays according to the invention, the X-ray source, which is disposed at the first focal point of the composite monochromator, generates an X-ray beam which is collected and reflected by the composite monochromator. The composite monochromator can re-generate the X-ray beam toward the second focal point of the composite monochromator with a high intensity.